1. Field of the Invention
The invention relates to a computer system and, more particularly, to a system end of the computer system is in a reading mode and the computer is working in a suspend mode to save power.
2. Description of the Related Art
FIG. 1 is a schematic diagram showing a conventional computer system. The conventional computer system 10 mainly includes a processor 122, a north bridge chip 124, a south bridge chip 126, an image buffer 142, an image transmitter 144 and a display panel 146. The north bridge chip 124 includes a memory controller 152 and a graphics controller 154. The north bridge chip 124 is connected between the processor 122 and the south bridge chip 126; the image buffer 142 is connected to the memory controller 152; the image transmitter 144 is connected to the image buffer 142, the graphics controller 154 and the display panel 146. The computer system also includes a keyboard (not shown) and a mouse (not shown) connected to the south bridge chip 126, and the operating relation between them and the computer system is omitted herein.
When the computer system 10 is powered on, the graphics controller 154 detects various parameters of the display panel 146 first, such as the maximum resolution supported by the display panel 146, and outputs a display panel parameter signal to the image transmitter 144. The graphics controller 154 is communicated with the display panel 146 according to the detecting result. When the user operates the computer system 10 with the keyboard or the mouse, the processor 122 temporarily stores the frame data to the image buffer 142 via the memory controller 152 according to the operation at an operating system of the computer system 10. The frame data represents images corresponding to the user's operation in the operating system. At the same time, the image transmitter 144 also points to the frame data that temporarily stored in the image buffer 142 simultaneously, and converts the read frame data to an image data with a constant frame rate and sends it to the display panel 146 according to the read frame data and the previously received display panel parameter signal. The frame data includes data such as RGB, horizontal synchronous (Hsyn), vertical synchronous (Vsyn), and the image transmitter 144 can converts the frame data to an image data with another specification, such as a low-voltage differential signaling (LVDS), and sends it to the display panel.
For example, if when the computer system 10 is powered on, the graphics controller 154 detects that the resolution of the display panel 146 is 800×600, and after the image transmitter 144 reads the frame data temporarily stored in the image buffer 142, the image transmitter 144 should convert the read frame data to an image data with a resolution of 800×600, and then outputs it to the display panel 146 for displaying the images corresponding to the image data.
In sum, the frame data of the image buffer 142 is updated continually via the processor 122 and the memory controller 152, and the image transmitter 144 also continually reads the frame data of the image buffer 142, converts it to the image data, and outputs the image data to the display panel 146. The user can get the change of the operations at the operating system synchronously via the display panel 146.
However, if the user only uses the operating system of the computer system 10 to read a document (such as a Word or a PDF document) and does not need to edit the document, the user may spend several or dozens of minutes on reading one page of the document without operating the operating system of the computer system 10 during the reading. However, during the several or dozens minutes in reading the same page of the document, the processor 122 of the conventional computer system 10 is still in a normal mode and monitors whether the user gives any new operating command, which wastes energy of the computer system 10.